The invention relates to an apparatus for the air-conditioning of the interior of automobiles, with a refrigerant circuit which consists of a low-pressure part and a high-pressure part and in which the vaporous refrigerant is drawn off from an evaporator by a compressor and, while experiencing an increase in pressure, is fed to a condenser for cooling and condensation, and the condensed refrigerant is collected in a collecting vessel, from which it can be diverted via an expansion valve into the evaporator, while experiencing a pressure drop and cooling, a pressure-release valve with a blow-off outlet being provided between the compressor and the condenser in the high-pressure part of the refrigerant circuit.
To allow such apparatuses to have as light-weight a construction as possible, the maximum pressure in the refrigerant circuit is limited by the pressure-release valve. In accordance with SAE standard J 639 applicable at the present time, the refrigerant pressure in an air-conditioning system of a vehicle may not exceed 35.5 bar for a refrigerant R12 and 44.4 bar for a refrigerant R22. When these pressures are exceeded, the refrigerant is blown off into the environment. According to the standard named, the high-pressure part of the refrigerant circuit must have a bursting pressure of at least 2.5 times the maximum pressure.
Under particularly adverse operating conditions, especially very high outside temperatures and the lack of any head wind and consequently a considerable break-down in the removal of heat, the maximum pressure can be exceeded and a blow-off of the refrigerant can occur. According to recent findings, the refrigerants conventionally used are harmful to the environment. Futhermore, the blownoff refrigerant is then lacking later when the apparatus is operating normally.